What is causing global temperatures to rise, and why is the Arctic warming at almost 4 times the rate as the rest of the globe?
Author
Earth & Space Science
HS-ESS2-2HS-ESS2-4HS-ESS2-6Time: 7-9 Days
19 Investigative Phenomenon
19.1 🌡️ Arctic Amplification
The globe is warming, and the average temperature of the Arctic is increasing at almost 4 times the rate as the rest of the globe.
19.1.1 Driving Questions:
What is causing global temperatures to rise today?
Why is the Arctic warming almost 4x faster than the rest of the globe?
How do feedbacks (like greenhouse gases and ice) amplify or reduce change?
How do greenhouse gas increases connect to glacial cycles and current warming?
20 Engage: Arctic vs Global Warming
What is happening to temperatures and Arctic ice today? Use the graph below to compare warming in the Arctic to the global average and surface student questions about the current climate change that orbital factors did not explain in the previous lesson.
Code
Plot =require("@observablehq/plot")arcticData = [ {year:1980,global:0.26,arctic:0.4}, {year:1985,global:0.12,arctic:0.3}, {year:1990,global:0.45,arctic:0.8}, {year:1995,global:0.45,arctic:0.9}, {year:2000,global:0.42,arctic:1.0}, {year:2005,global:0.69,arctic:1.5}, {year:2010,global:0.72,arctic:1.8}, {year:2015,global:0.90,arctic:2.5}, {year:2020,global:1.02,arctic:3.2}, {year:2024,global:1.29,arctic:4.1}]Plot.plot({title:"Temperature Change: Arctic vs Global Average",subtitle:"Anomaly relative to 1951-1980 baseline (°C)",width:700,height:400,y: {label:"Temperature Anomaly (°C)",domain: [0,4.5]},x: {label:"Year"},color: {legend:true},marks: [ Plot.line(arcticData, {x:"year",y:"arctic",stroke:"#3498db",strokeWidth:3}), Plot.line(arcticData, {x:"year",y:"global",stroke:"#e74c3c",strokeWidth:3}), Plot.dot(arcticData, {x:"year",y:"arctic",fill:"#3498db",r:5}), Plot.dot(arcticData, {x:"year",y:"global",fill:"#e74c3c",r:5}), Plot.text([{x:2010,y:2.3}], {x:"x",y:"y",text: d =>"Arctic",fill:"#3498db",fontSize:14,fontWeight:"bold"}), Plot.text([{x:2010,y:0.5}], {x:"x",y:"y",text: d =>"Global",fill:"#e74c3c",fontSize:14,fontWeight:"bold"}) ]})
20.0.1 🤔 Initial Questions
How much faster is the Arctic warming compared to the global average?
What evidence from the graph suggests the Arctic is changing more rapidly?
What changes in the Arctic might amplify or reduce this warming trend?
(a) Atmospheric CO₂ concentration and Antarctic temperature over the past 800,000 years, showing strong correlation during glacial-interglacial cycles and unprecedented current CO₂ levels.
(b)
Figure 20.1
21 Explore Part 1: The Greenhouse Effect
How do carbon dioxide levels in the air both impact and change as a result of Earth’s systems? Use the simulation to gather evidence about the causal mechanism behind the correlation between atmospheric CO₂ levels and climate factors like temperature.
21.1 Modeling the Effect of the Carbon Cycle on Temperature
Explore how greenhouse gases trap heat in Earth’s atmosphere:
Some previews (and some LMS pages) block external iframes, so this lesson uses a click-to-open launch card instead of an embed.
21.1.1 🔬 Simulation Investigation Tasks
Task 1: Explore the Greenhouse Effect 1. Start with “Waves” mode to see how infrared radiation interacts with greenhouse gases 2. Compare Earth’s temperature with NO greenhouse gases vs. with greenhouse gases 3. Record the equilibrium temperature for each scenario
Task 2: Compare Different Atmospheres 1. Try the Ice Age atmosphere setting 2. Try the 1750 (pre-industrial) setting 3. Try the “Today” setting 4. Record how temperature changes with different CO₂ levels
Task 3: Photon Absorption 1. Switch to “Photons” mode 2. Observe what happens when infrared photons encounter CO₂ molecules 3. Explain why more CO₂ = more warming
21.2 CO₂ and Temperature: The Evidence
21.2.1 Ice Core Data: 800,000 Years of CO₂ and Temperature
Code
// Ice core CO2 and temperature dataiceCoreData = [ {kya:800,co2:190,temp:-8}, {kya:700,co2:210,temp:-6}, {kya:600,co2:240,temp:-4}, {kya:500,co2:200,temp:-7}, {kya:400,co2:180,temp:-9}, {kya:350,co2:200,temp:-6}, {kya:300,co2:240,temp:-3}, {kya:250,co2:200,temp:-7}, {kya:200,co2:190,temp:-8}, {kya:150,co2:220,temp:-5}, {kya:130,co2:280,temp:2}, {kya:100,co2:230,temp:-4}, {kya:50,co2:200,temp:-6}, {kya:20,co2:180,temp:-9}, {kya:10,co2:260,temp:-1}, {kya:0.2,co2:280,temp:0}, {kya:0,co2:420,temp:1.2}]
Code
viewof showModern = Inputs.toggle({label:"Show modern CO₂ level (420 ppm)",value:false})
Code
displayData = showModern ? iceCoreData : iceCoreData.filter(d => d.kya>0.1)Plot.plot({title:"CO₂ Concentration Over 800,000 Years",subtitle:"Data from Antarctic ice cores",width:750,height:350,x: {label:"Thousands of Years Ago",reverse:true,domain: [800,0]},y: {label:"CO₂ (ppm)",domain: [150, showModern ?450:320]},marks: [ Plot.ruleY([280], {stroke:"#999",strokeDasharray:"4,4"}), Plot.line(displayData, {x:"kya",y:"co2",stroke:"#27ae60",strokeWidth:2}), Plot.dot(displayData.filter(d => d.kya===0), {x:"kya",y:"co2",fill:"#e74c3c",r:10}), Plot.text([{x:400,y:295}], {x:"x",y:"y",text: d =>"Pre-industrial maximum: 280 ppm",fill:"#999",fontSize:11}), showModern ? Plot.text([{x:50,y:420}], {x:"x",y:"y",text: d =>"TODAY: 420 ppm",fill:"#e74c3c",fontSize:12,fontWeight:"bold"}) :null ].filter(d => d !==null)})
21.2.2 ✅ Data Analysis
What is the highest CO₂ level in the past 800,000 years (before humans)?
What is today’s CO₂ level?
How does today’s CO₂ compare to the natural range?
What pattern do you notice between CO₂ and temperature in the ice core record?
Based on these data, make a claim about how CO₂ levels and temperature are related.
22 Explore Part 2: The Albedo Effect
How is the icy surface of the poles changing, and what does that do to Earth’s temperature? Analyze albedo models and datasets to figure out how different surfaces change the surrounding system and impact temperature.
22.1 What is Albedo?
Albedo is the measure of how much light a surface reflects. It ranges from 0 (absorbs all light) to 1 (reflects all light).
June 14, 2023
July 24, 2023
Drag the slider left and right to compare the images
Figure 22.1: Interactive comparison of Frederiksdal Glacier, Greenland between June 14 and July 24, 2023, showing dramatic ice loss over 40 days.
Code
albedoData = [ {surface:"Fresh Snow",albedo:0.85,color:"#ffffff"}, {surface:"Sea Ice",albedo:0.60,color:"#b3e5fc"}, {surface:"Old Snow",albedo:0.45,color:"#e0e0e0"}, {surface:"Desert Sand",albedo:0.40,color:"#fdd835"}, {surface:"Grassland",albedo:0.25,color:"#81c784"}, {surface:"Forest",albedo:0.15,color:"#2e7d32"}, {surface:"Ocean Water",albedo:0.06,color:"#1565c0"}, {surface:"Asphalt",albedo:0.04,color:"#37474f"}]Plot.plot({title:"Albedo of Different Surfaces",subtitle:"Higher albedo = more reflection = less heating",width:700,height:400,x: {label:"Albedo (reflection coefficient)",domain: [0,1]},y: {label:"Surface Type",domain: albedoData.map(d => d.surface)},marks: [ Plot.barX(albedoData, {x:"albedo",y:"surface",fill:"color",sort: {y:"-x"}}), Plot.text(albedoData, {x:"albedo",y:"surface",text: d => (d.albedo*100).toFixed(0) +"%",dx:25,fontSize:12}) ]})
PBS LearningMedia resources work best when opened in a new browser tab. If blocked, check your school network settings.
Figure 22.2: Interactive glacier photo comparison showing dramatic glacial retreat over time. Drag the slider to compare images. (Source: PBS LearningMedia)
23 Explain Part 1: CO₂–Temperature Connection
How are atmospheric carbon dioxide levels and temperatures related? Construct an explanation using evidence from the simulation, ice core data, and text, describing how human activities have increased greenhouse gas levels and how that drives warming.
24 Explain Part 2: Feedback Loops in the Climate System
24.1 🔄 Understanding Climate Feedbacks
A feedback loop occurs when the output of a system affects its input, creating a cycle.
24.1.1 Positive Feedback (Amplifying)
Makes changes BIGGER - the system amplifies itself
24.1.2 Negative Feedback (Stabilizing)
Makes changes SMALLER - the system stabilizes itself
What type of feedback is the ice-albedo feedback? (positive or negative)
Why does exposing dark ocean water lead to more warming?
Calculate: If ice (albedo 0.6) is replaced by ocean (albedo 0.06), how much more energy is absorbed?
How does the ice-albedo feedback help explain why the Arctic warms faster than the rest of the planet?
25 Elaborate: Greenhouse Gases + Albedo Together
How do greenhouse gases and albedo interact? Model the combined effects of greenhouse gas and albedo feedback loops to explain the rapid rate of change of Earth’s temperature and make claims about what could happen in the future based on historical and current evidence.
25.1 CO₂ and Human Activity
25.2 Where Does the CO₂ Come From?
Code
co2SourcesData = [ {source:"Electricity & Heat",emissions:25,color:"#e74c3c"}, {source:"Transportation",emissions:16,color:"#3498db"}, {source:"Manufacturing",emissions:21,color:"#f39c12"}, {source:"Agriculture & Land Use",emissions:24,color:"#27ae60"}, {source:"Buildings",emissions:6,color:"#9b59b6"}, {source:"Other Energy",emissions:8,color:"#95a5a6"}]Plot.plot({title:"Global Greenhouse Gas Emissions by Sector",width:600,height:400,x: {label:"Percentage of Global Emissions"},y: {label:"Sector",domain: co2SourcesData.map(d => d.source)},marks: [ Plot.barX(co2SourcesData, {x:"emissions",y:"source",fill:"color",sort: {y:"-x"}}), Plot.text(co2SourcesData, {x:"emissions",y:"source",text: d => d.emissions+"%",dx:20,fontSize:12,fontWeight:"bold"}) ]})
The greenhouse effect explains why increasing CO₂ leads to global warming
Albedo is the tendency of a surface to reflect or absorb radiation
Ice has high albedo (~60%) compared to seawater (~6%)
As ice melts, more radiation is absorbed, causing more warming → positive feedback
Arctic amplification (4x faster warming) is explained by ice-albedo feedback
Multiple feedback loops (ice-albedo, water vapor, permafrost) amplify climate change
Human activities have dramatically increased CO₂ levels beyond natural ranges
26 Evaluate: Modeling Climate Feedbacks
26.1 📊 Performance Task Check-In
Using what you’ve learned, you can now explain:
Why scientists are confident humans are causing climate change:
CO₂ levels are far beyond natural range (420 ppm vs. max 280 ppm)
The timing matches industrialization
Natural factors (Milankovitch cycles, solar output) can’t explain current warming
Why the Arctic is warming so fast:
Ice-albedo feedback amplifies warming
As ice melts, dark ocean absorbs more energy
This creates a self-reinforcing cycle
How feedbacks make climate change worse:
Ice-albedo: melting ice → more absorption → more melting
Water vapor: warming → more evaporation → more greenhouse effect
Permafrost: warming → methane release → more warming
Claim with evidence: Use data from this lesson to explain how human activities are driving destabilizing feedback loops today.
26.2 Create Your Feedback Diagram
26.2.1 📝 Activity: Draw Your Own Feedback Loop
Create a diagram showing how multiple feedback loops interact:
Start with “Human emissions increase CO₂”
Show how this leads to warming
Include ice-albedo feedback
Include water vapor feedback
Show how they connect and amplify each other
Indicate which parts are observed data vs. projected consequences
Guiding Questions: - Where do humans enter this system? - Which parts of the cycle have we already observed? - What might happen if Arctic ice disappears entirely in summer? - Are there any potential negative (stabilizing) feedbacks?
27 Interactive Carbon Cycle Flow Diagram
This visualization shows how carbon flows between Earth’s major reservoirs changed after the Industrial Revolution.
md`### Key Changes After Industrial Revolution:- **Atmospheric CO₂ increased by ${atmosphereChange} Gt** (${((atmosphereChange/carbonData.preIndustrial.atmosphere)*100).toFixed(1)}% increase)- **${fossilFuelBurned} Gt of fossil fuels burned** and added to atmosphere- **Ocean absorbed ${carbonData.postIndustrial.ocean- carbonData.preIndustrial.ocean} Gt** more carbon- **The carbon cycle became unbalanced** - more carbon entering atmosphere than leaving`
28 Feedback Loop Visualization
This visualization shows how positive feedback mechanisms amplify climate change through interconnected processes.
// Get current loopcurrentLoop = feedbackType ==="Ice-Albedo Feedback"? feedbackLoops.iceAlbedo: feedbackType ==="Greenhouse Gas Feedback"? feedbackLoops.greenhouseGas: feedbackLoops.combined
// Explanatory textmd`### Understanding Positive Feedbacks${feedbackType ==="Ice-Albedo Feedback"?`**Ice-Albedo Feedback** occurs when warming melts reflective ice and snow, exposing darker surfaces (ocean, land) that absorb more solar radiation. This extra absorption causes more warming, which melts more ice - a self-reinforcing cycle that **amplifies** the initial warming.**Key Point:** Arctic regions are warming **~4 times faster** than the global average due to this feedback!`: feedbackType ==="Greenhouse Gas Feedback"?`**Greenhouse Gas Feedback** happens when warming temperatures cause natural systems to release stored carbon. Warmer oceans hold less dissolved CO₂, and thawing permafrost releases both CO₂ and methane. These additional greenhouse gases trap more heat, causing further warming and more release.**Key Point:** This creates a situation where human-caused warming **triggers natural carbon releases** that we don't directly control.`:`**Combined Feedbacks** show how multiple reinforcing mechanisms work together to amplify warming far beyond the initial forcing from fossil fuel emissions. Each feedback strengthens the others:- More GHGs → More warming → Ice melts → Less reflection → Even more warming- More warming → Ocean/permafrost release CO₂ → More GHGs → Even more warming**Key Point:** The **rate of current warming** (0.2°C per decade) is unprecedented in the last 2,000 years because these feedbacks amplify the human-caused forcing.`}⚠️ **Why this matters:** These are called **positive feedbacks** not because they're good, but because they **amplify change** rather than damping it. Once triggered, they make climate change harder to stop.`
28.1 📝 Climate Feedbacks Quiz (Click to Reveal Answers)
Question 1: What is the primary greenhouse gas that humans have increased in the atmosphere? - A) Oxygen - B) Nitrogen - C) Carbon dioxide - D) Argon
Show answer
Answer: C) Carbon dioxide
Question 2: What is albedo? - A) The amount of CO₂ in the atmosphere - B) The measure of how much light a surface reflects - C) The temperature of the ocean - D) The speed of ice melting
Show answer
Answer: B) The measure of how much light a surface reflects
Question 3: Which surface has the HIGHEST albedo? - A) Fresh snow - B) Ocean water - C) Forest - D) Desert sand
Show answer
Answer: A) Fresh snow
Question 4: The ice-albedo feedback is an example of: - A) Negative feedback that stabilizes climate - B) Positive feedback that amplifies warming - C) No feedback effect - D) A cooling mechanism
Show answer
Answer: B) Positive feedback that amplifies warming
Question 5: Why is the Arctic warming almost 4 times faster than the global average? - A) The Sun is closer to the Arctic - B) Ice-albedo feedback amplifies warming there - C) There are more people in the Arctic - D) Volcanic activity in the Arctic
Show answer
Answer: B) Ice-albedo feedback amplifies warming there
Question 6: Current atmospheric CO₂ levels are approximately: - A) 280 ppm (pre-industrial level) - B) 350 ppm - C) 420 ppm - D) 1000 ppm
Show answer
Answer: C) 420 ppm
Question 7: In the greenhouse effect, what type of radiation do greenhouse gases absorb? - A) Visible light from the Sun - B) Ultraviolet radiation - C) Infrared radiation from Earth’s surface - D) X-rays
Show answer
Answer: C) Infrared radiation from Earth’s surface
Question 8: The permafrost feedback involves the release of which gases? - A) Oxygen and nitrogen - B) Methane and carbon dioxide - C) Ozone and CFCs - D) Hydrogen and helium
Show answer
Answer: B) Methane and carbon dioxide
Question 9: If Arctic sea ice (albedo 0.60) is replaced by open ocean (albedo 0.06), what happens to energy absorption? - A) Stays the same - B) Decreases slightly - C) Increases dramatically (10x more absorbed) - D) Decreases dramatically
Show answer
Answer: C) Increases dramatically (10x more absorbed)
Question 10: Which statement best explains why scientists are confident humans are causing current climate change? - A) It’s just a guess - B) Temperatures have changed before naturally - C) CO₂ levels are far beyond natural range and match timing of industrialization - D) The Sun has gotten brighter
Show answer
Answer: C) CO₂ levels are far beyond natural range and match timing of industrialization